/Engine/Plugins/Experimental/GeometryScripting/Source/GeometryScriptingCore/Public/GeometryScript/MeshQueryFunctions.h
Returns the 3D positions (in the mesh local space) of the three vertices of the requested triangle. If the Triangle ID is not an element of the Target Mesh, all three vertices will be returned as (0, 0, 0) and bIsValidTriangle will be set to false.
[UFUNCTION](Programming/UnrealArchitecture/Reference/Functions)(BlueprintPure, Category="GeometryScript|MeshQueries", Meta=(ScriptMethod)) static void GetTrianglePositions ( [UDynamicMesh](API\Runtime\GeometryFramework\UDynamicMesh) * TargetMesh, int32 TriangleID, bool & bIsValidTriangle, FVector & Vertex1, FVector & Vertex2, FVector & Vertex3 )